1. Field of Invention
The present invention generally relates to swim fins and, in particular, to retractable swim fins that attach to the legs of a swimmer to aid movement through the water.
2. Description of Related Art
Typical swim fins are worn on the foot of a swimmer to aid movement through the water while surface swimming or participating in swimming-related activities such as bodyboarding, bodysurfing, kneeboarding, riverboarding, snorkeling, and various types of underwater diving. For example, scuba divers use swim fins to move through water efficiently, as human feet provide relatively poor thrust, especially when the diver is carrying equipment that increases hydrodynamic drag.
Unfortunately, typical swim fins have several problems. For example, since typical swim fins attach only to the foot and heel of a swimmer, typical swim fins can cause severe ankle strain and calf muscle fatigue. This is due to the mass of water moved by the fin and the fact that the ankle joint rotates through a complex, non-planar, arc. Further, the ankle does not generally orient the foot optimally for forward thrust, thus reducing the efficiency of the hydrofoil properties of the fin. Further, typical swim fins increase the footprint of the swimmer and are constructed of heavy and bulky materials, thus making it difficult to walk, as is often necessary when entering or exiting water via a shoreline, a boat, or a dock.
Another major problem with typical swim fins is related to an integral foot pocket which at least partially encloses the foot of the swimmer. Unfortunately, foot pockets tend to inadvertently gather foreign objects such as sand or gravel which can chafe the foot of the swimmer making swimming and walking uncomfortable or even painful, and can further risk infection. Also, foot pockets tend to retain some water which can be uncomfortable because the foot of the swimmer does not dry even when the swimmer is out of the water. Further, it can be difficult or impossible to clear foreign objects or water from the foot pocket without completely removing the swim fin from the foot of the swimmer. Also, foot pockets tend to restrict the other types of footwear, such as sandals or water socks, that can simultaneously be worn. Finally, foot pockets deprive the swimmer of the joyful sensation of walking bare-footed across the warm sand of a sandy beach or the cool grass of a grassy lawn.